The seroprevalance of Crimean-Congo haemorrhagic fever in people living in the same environment with Crimean-Congo haemorrhagic fever patients in an endemic region in Turkey

Crimean-Congo haemorrhagic fever (CCHF) is endemic in Turkey, and since 2004 many cases have been reported from different regions of Turkey. There are limited data about the seroprevalence of the disease in household members of patients or persons sharing the same environment. We evaluated seroprevalence of CCHF in the immediate neighbourhood and in household members of patients living in the same environment as confirmed cases of CCHF in an endemic area of Turkey. A total of 625 healthy subjects [mean (s.d.) age: 42 center dot 3 (18 center dot 4) years, 58 center dot 7% females] without a past history of CCHF infection included in this case-control, retrospective study were evaluated in terms of sociodemographic characteristics, risk factors for CCHF via a study questionnaire, while serum analysis for CCHF virus (CCHFV) IgG antibodies was performed by ELISA. Anti-CCHFV IgG antibodies were positive in 85 (13 center dot 6%) participants. None of the seropositive individuals had a history of symptomatic infection. Regression analysis revealed that animal husbandry [odds ratio (OR) 1 center dot 84, 95% confidence interval (CI) 1 center dot 09-3 center dot 11], contact with animals (OR 2 center dot 31, 95% CI 1 center dot 08-5 center dot 10), contact with ticks (OR 3 center dot 45, 95% CI 1 center dot 87-6 center dot 46), removing ticks from animals by hand (OR 2 center dot 48, 95% CI 1 center dot 48-4 center dot 18) and living in a rural area (OR 4 center dot 05, 95% CI 1 center dot 65-10 center dot 56) were associated with increased odds of having IgG seropositivity, while being a household member of a patient with prior CCHF infection had no influence on seropositivity rates. This result also supports the idea that CCHF is not transmitted person-to-person by the airborne route.